This invention relates to a process for preparing halo-benzophenones and intermediates made in their preparation. In particular, it relates to a process for preparing 4,4'-difluorobenzophenone.
The compound 4,4'-difluorobenzophenone is useful in making high molecular weight polyetheretherketones (PEEK). See, for example, U.S. Pat. No. 3,320,224, herein incorporated by reference. At the present time, 4,4'-difluorobenzophenone is made commercially by a process described in U.S. Pat. No. 4,263,458. In that process, methylene dianiline is reacted with hydrogen fluoride to produce the fluoride salt. This fluoride salt is explosive and handling large quantities of it can present a considerable safety hazard. In the next step, the fluoride salt is thermally decomposed and oxidized to form 4,4'-difluorobenzophenone. Because of the explosive nature of the fluoride salt a less dangerous chemical route to produce the product would be desirable.